Propofol Formulations with Non-Reactive Container Closures

ABSTRACT

A container storing an anesthetic is disclosed. The container is sealed by a closure and stores a liquid anesthetic solution. The anesthetic is from 0.1% to 10% by weight of the liquid anesthetic solution. The container is made of a material that is inert to the anesthetic and the closure is made of siliconized rubber or a metal. A concentration of the anesthetic in a liquid anesthetic solution stored in the container following a predetermined time period is at least 93% of a concentration of the anesthetic in a liquid anesthetic solution before the liquid anesthetic solution is stored in the container.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 10/616,709,filed on Jul. 10, 2003, the disclosure of which are incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The invention generally pertains to pharmaceutical formulations ofpropofol, an intravenous anesthetic with enhanced microbial inhibition.More particularly, the invention pertains to propofol formulations thatare stored in containers having non-reactive, or inert closures.

BACKGROUND OF THE INVENTION

Propofol (2,6-Diisopropylphenol) is a well-known and widely usedintravenous anesthetic agent. For example, in intensive care units (ICU)where the duration of treatment may be lengthy, propofol has theadvantage of a rapid onset after infusion or bolus injection plus a veryshort recovery period of several minutes, instead of hours.

Propofol is a hydrophobic, water-insoluble oil. To overcome thesolubility problem, it must be incorporated with solubilizing agents,surfactants, solvents, or an oil in water emulsion. There are a numberof known propofol formulations, such as disclosed in U.S. Pat. Nos.4,056,635, 4,452,817 and 4,798,846 all of which are issued to Glen andJames.

Propofol compositions have been the subject of several patents.Typically, propofol compositions comprise 1-2% by weight propofol, 1-3%or 10-30% of a water immiscible solvent such as soybean oil, 1.2% of egglecithin as a surfactant, and 2.25% glycerin as a tonicity agent.Variation in pH and/or addition of other components allows for variousadvantages and uses. For example, Hendler (U.S. Pat. No. 6,362,234) usespropofol esters (100 mg-3 gm) in combination with anti-migraines to makeaqueous, solid and other non-aqueous compositions for internal andtransdermal delivery, for the treatment of migraines. De Tommaso (U.S.Pat. No. 6,326,406) discloses a composition of pH 4.5-6.5 comprising 10mg/ml propofol, 25-150 mg/ml bile salt, a lecithin, and preparation withsubstantially no oxygen. Mixing propofol with bile acid produces a clearformulation and allows for easy detection of foreign particles. Forveterinary applications, benzyl alcohol and phospholipid freecomposition comprising from 1-30% by weight propofol, wherein theaqueous solution is sterile filtered has been used to anesthetizeanimals (Carpenter, U.S. Pat. No. 6,150,423). Higher percentages ofpropofol allow for administration of smaller quantities.

To prevent microbial growth, various components and methods ofpreparation have been discussed. For example, Mirejovsky, et al.,disclose compositions of pH 4.5-6.4 with less than 1% sulfites and 1-2%by weight propofol (U.S. Pat. Nos. 6,469,069 and 6,147, 122); George, etal., disclose 0.15-0.25% tromethamine with 1-2% by weight propofol andpH 8.5-10 (U.S. Pat. No. 6,177,477); 0.005% EDTA with 1-2% by weightpropofol and pH 6-8.5 has been used by Jones, et al., (U.S. Pat. Nos.5,714,520, 5,731,355, and 5,731,356); George (U.S. Pat. No. 6,028,108),discloses compositions with 0.005-0.1% pentetat that are 1-2% by weightpropofol and pH 6.5-9.5. Likewise, lowering pH ranges (pH 5-7), usingegg lecithin (0.2-1%) and soybean oil (1-3%), without preservatives and0.1-6% propofol by weight (Zhang, et al., U.S. Pat. No. 6,399,087), andlowering concentrations of soybean oil (1-3%) to produce stableemulsions and reducing nutrients with 1% propofol by weight (Pejaver, etal., U.S. Pat. No. 6,100,302), are said to provide protection againstmicrobial contamination. Reducing lipid concentrations also reduces thechances of fat overload and is ideal for use when administered overextended time periods. In addition, compositions devoid of fats andtriglycerides, with 3% w/v propofol (Haynes, U.S. Pat. No. 5,637,625)are said to be useful for sedation over extended periods of time.

There are two major problems associated with the formulations describedin the above patents: (1) the risk of microbial contamination due to thehigh nutrient content and lack of antimicrobial preservatives. Studiesby Arduino, et al., 1991; Sosis & Braverman, 1993; and PDR, 1995, haveshown that a propofol emulsion formulated without preservatives willgrow bacteria and present a risk of bacterial contamination; (2)Hyperlipidemia in patients undergoing long-term ICU sedation due to alarge amount of fat content. Studies have shown that triglycerideoverload can become a significant problem when a 1% propofol/10% soybeanoil emulsion is used as the sole sedative for a long period of ICUsedation by Gottardis, et al., 1989; DeSoreruer, et al., 1990; Lindholm,1992; and Eddieston, et al, 1991.

To solve the problem of bacterial contamination of propofol emulsion,the following patented formulations of propofol have been developed:

Pat. No. Inventor Issued 5,637,625 Duncan H. Haynes 10 Jun. 19975,714,520 Christopher B. J., et al. 3 Feb. 1998 6,028,108 Mary M. G. 22Feb. 2000 6,100,302 Satish K. P., et al. 8 Aug. 2000 PCT 99/39696Mirejovsky D., et al. 12 Aug. 1999 PCT 00/24376 Mary T., et al. 4 May2000

The formulations described in U.S. Pat. No. 5,714,520 is sold asDIPRIVAN® and comprises a sterile, pyrogen-free emulsion containing 1%(W/v) propofol in 10% (w/v) soybean oil. The formulation also contains1.2% (w/v) egg lecithin as a surfactant, 2.25% (w/v) glycerol to makethe formulation isotonic, sodium hydroxide to adjust the pH, and EDTA0.0055% (w/v) as a preservative. This formulation prevents no more thana 10-fold increase against gram negative (such as Pseudomonas aeruginosaand Escherichia coli) and gram positive (Staphylococcus aureus)bacteria, as well as yeast (such as Candida albicans) over a twenty-fourhour period. However, EDTA, which is a metal ion chelator, removescations like calcium magnesium and zinc. This can be potentiallydangerous to some patients with low calcium or other low cation levels,and especially critical for ICU patients.

In U.S. Pat. No. 6,028,108 the propofol formulation contains pentetate0.0005% (w/v) as a preservative to prevent microbial contamination.Pentetate is a metal ion chelator similar to EDTA and thereforerepresents the same potential danger.

The formulation described in W.O. Patent No. 99/39696, is genericpropofol containing 0.25 mg/mL sodium metabisulfite as a preservative toprevent microbial growth. At 24 hours there is no more than a one logincrease. Recently, P. Langevin, 1999, has expressed concern thatgeneric propofol containing 0.25 mg/mL sodium metabisulfite, infused ata rate of 50 ug/kg/min, will result in sulfite administrationapproaching the toxic level (i.e., near the LD50 for rats) in about 25hours.

Particularly, the addition of sulphites to this drug is worrisome forthe potential effects to the pediatric population and for sulphurallergy to the general population. In a June 2000 letter, themanufacturer of metabisulphite-containing propofol emulsion (GensiaSicor) stated that discoloration and a reduction in pH occur when theproduct is exposed to air and that both phenomena are caused by theoxidation of sodium metabisulphite Mirejovsky D. Ghosh M. Reply.(Pharmaceutical and antimicrobial differences between propofol emulsionproducts) (Am J Health-Syst Pharm. 2000: 57:1176-7). Results show thatthe yellowing of the commercial metabisulphite-containing propofolemulsion is an oxidized form of propofol dimer quinine which is lipidsoluble. (U.S. Pat. No. 6,399,087). Recent data also support pro-oxidantactivity by the sulfite anion resulting in propofol dimerization andlipid peroxidation (Baker et al., Anesthesiology, 96, A472, 2002).

The formulation described in PCT W.O. Patent No. 00/24376 is aformulation having an antimicrobial agent, which is a member selectedfrom the group consisting of benzyl alcohol and sodium ethylenediaminetetraacetate, benzethonium chloride; and benzyl alcohol and sodiumbenzoate. The formulation contains EDTA, which was mentioned as relatedto the side effect above. Benzyl alcohol is linked to adverse reactionsreported by Evens and Lopez-Herce, et al. The formulation may be unsafeupon administration, particularly to those patients who need an extendedperiod of ICU sedation.

The formulation described in U.S. Pat. No. 5,637,625 is ofphospholipid-coated microdroplets of propofol, containing 6.8% propofolwith no soybean oil. However, it is believed that this formulation mayincrease injection site pain to an unacceptable level duringadministration.

The formulation described in U.S. Pat. No. 6,100,302 is an emulsion ofpropofol that contains 1-3% of soybean oil to prevent against accidentalmicrobial contamination during long-term IV infusions due to anincreased availability of propofol.

Egg lecithin is mainly used in pharmaceutical products as a dispersing,emulsifying, and stabilizing agent. The lecithin is also used ascomponent of enteral and paranteral nutrition formulations, Arthur H.Kibbe, 2000.

It has been also found that in this invention a propofol formulationcontaining a reduced amount of egg lecithin results in a significantincrease in the ability to be antimicrobial. The soybean oil is alsosource of nutrition to support the microbial growth.

Thus, it has been found that the preservative-free, optimized propofolformulation of this invention addresses the prior art problems to thepoint where the problems are eliminated or at the least aresubstantially reduced.

It has now been discovered that the propofol in propofol formulationswith reduced oil content is degraded when stored in a container with aclosure that is not inert to propofol. The problem of propofoldegradation encountered was quite unexpected as closures sealed with arubber stopper or the like are known. For example, U.S. Pat. No.6,576,245 points out that primary packages such as vials, bottles,cartridges, prefilled syringes and the like are typically sealed by arubber stopper or plunger. U.S. Pat. No. 6,576,245 further expresses apreference for a rubber material containing bromobutyl instead ofchlorobutyl to improve the stability of low molecular weight thrombininhibitors in solution. Heretofore, however, the art has not understoodthat the propofol in propofol formulations is susceptible to degradationdue to exposure to the closure for the container. The failure of the artto recognize the effect of the container closure on propofoldegradation, it is believed, is due to the fact that the commerciallyavailable propofol formulation DIPRIVAN® comprises 10% (w/v) soybeanoil. Applicants have found that at the relatively high volume of soybeanoil used in prior art formulations, the soybean oil apparently protectspropofol from degradation. However, at oil contents (and/or propofolsolvent contents) lower than about 10% (w/v), degradation of propofolhas been found to occur if the container closure is not inert ornon-reactive to propofol.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention in one of its embodiments provides asterile formulation of propofol for parenteral administration containinga reduced amount of egg lecithin and soybean oil triglycerides. Theformulation is preferably comprised of an oil in water emulsion with amean particle size of from about 100 to about 300 nanometers indiameter, in which the propofol is dissolved in a water-immisciblesolvent such as soybean oil, and stabilized by a surfactant such as egglecithin. The composition preferably has a pH in the range of from aboutpH 5 to about pH 8. The low amount of lecithin and soybean oil in theformulation offers a number of advantages. In other embodiments of theinvention, the composition includes protein, such as albumin. Thepresence of protein such as albumin in the propofol formulation is alsoadvantageous. The advantages of the formulations in accordance with theembodiments of the invention include:

(1) eliminating preservatives, such as EDTA that can result in zinc lossdue to chelation,

(2) providing formulations with excellent exhibition of antimicrobialactivity compared to formulations with higher amount of lecithin and oilsolvent emulsion containing preservatives, and

(3) a reduced risk of hyperlipidemia in patients.

Further, the presence of protein, such as albumin in the propofolformulation reduces the propofol-induced pain on injection. Painreduction is due to binding of free propofol with albumin and consequentreduction of the free propofol injected. It has also been found that theprotein, and in particular, albumin, assists in forming the stabilizinglayer at the interface of the so-called oil phase and aqueous phase ofthe emulsion. Further, the use of protein provides for compositionswhich do not include a water-immiscible solvent for propofol or asurfactant or both. Thus, in one embodiment of the invention, there isprovided a sterile pharmaceutical composition for parenteraladministration of propofol, in which the composition comprises propofol,an aqueous phase and protein, such as albumin.

The propofol formulations of the present invention have no more than a10-fold increase in the growth of each of Pseudomonas aeruginosa,Escherichia coli, Staphylococcus aureus and Candida albicans for atleast 24 hours after adventitious, extrinsic contamination.

In a further embodiment of the present invention, the propofolcomposition is stored in a container that is inert or non-reactive andthat has an inert or non-reactive closure, such that the container andclosure do not cause significant degradation or loss in potency of thepropofol formulation. Thus, by way of illustration, the degradation orloss of potency of propofol should be such that the propofol compositionmeets regulatory safety and efficacy standards. As a result, impuritylevels, levels of degradation products, and potency loss are withinaccepted regulatory limits. The closure can itself be inert ornon-reactive, or the closure can be coated with a suitable coatingmaterial to make it non-reactive or inert.

These and other objects and advantages of the present invention willbecome apparent from the subsequent detailed description of thepreferred embodiment and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The invention in one of its embodiments is a sterile pharmaceuticalcomposition for parenteral administration comprised of an oil-in-wateremulsion, in which propofol is dissolved in a water-immiscible solvent,preferably soybean oil, and stabilized by a surfactant, preferably egglecithin. The composition further comprises a reduced amount of egglecithin and soybean oil to inhibit microbial contamination during IVinfusions over a period of time. In other embodiments of the invention,water immiscible solvents can also be used. The composition preferablycomprises protein, such as albumin which binds free propofol to reducethe pain on injection. In another embodiment, the invention comprisescompositions of propofol having no oil. In this embodiment, thecomposition also preferably comprises protein, such as albumin.

An oil-in-water emulsion is meant to be a distinct, two-phase systemthat is in equilibrium and in effect, as a whole, is kinetically stableand thermodynamically unstable. Thus, as used herein, the aqueous phaserefers generally to the phase which includes water or water of injectionwith or without other water soluble or water miscible components, andthe oil phase refers to the phase that includes propofol. The propofolmay be present neat, or with a solvent oil or other propofol misciblecomponent.

Prevention of a significant growth of microorganisms is meant to begrowth of microorganisms, which is preferably no more than a one logincrease following extrinsic contamination generally found in treatmentsettings such as ICU's and the like. For purposes of this definition,the contamination is commonly about 50-200 colony forming units/ml at atemperature in the range of 20-25° C.

The composition of the present invention typically comprises from 0.1%to 10% by weight of propofol, and, more preferably from 1 to 5%propofol. Preferably, the composition comprises 1%, 2% or 5% propofol.All references herein to weight percent are meant to be weight percentby volume of the composition.

The water miscible solvent or the water-immiscible solvent is present inan amount that is preferably from 0 to 10% by weight of the composition,and more preferably from 1 to 6% by weight of the composition for theformulation containing 0.5-5% propofol. Also preferred are compositionsthat contain no water-immiscible solvents so that the propofol ispresent neat.

The oil-in-water emulsion can be prepared by using neat propofol or bydissolving propofol in a solvent, and preparing an aqueous phasecontaining water of injection and optionally a surfactant, protein andother water-soluble ingredients, and then mixing the oil with theaqueous phase. The crude emulsion is homogenized under high pressure toprovide an emulsion.

A wide range of water-immiscible solvents can be used in the compositionof the present invention. Typically, the water-immiscible solvent is avegetable oil, for example, soybean, safflower, cottonseed, corn,coconut, sunflower, arachis, castor sesame, orange, limonene or oliveoil. Preferably, the vegetable oil is soybean oil. Alternatively, thewater-immiscible solvent is an ester of a medium or long-chain fattyacid, for example a mono-, di-, or triglyceride, or is a chemicallymodified or manufactured palmitate, glyceral ester or polyoxyl,hydrogenated castor oil. In a further alternative, the water-immisciblesolvent may be a marine oil, for example cod liver or other fish-derivedoil. Suitable solvents also include fractionated oils, for example,fractionated coconut oil, or modified soybean oil. Furthermore, thecomposition of the present invention may comprise a mixture of two ormore of the above water-immiscible solvents. Water-miscible solvents mayalso be utilized. Thus, for example, suitable solvents includechloroform, methylene chloride, ethyl acetate, ethanol, tetrahydrofuran,dioxane, acetonitrile, acetone, dimethyl sulfoxide, dimethyl formamide,methylpyrrolidinone, and the like. Additional solvents contemplated foruse in the practice of the present invention include C1-C20 alcohols,C2-C20 esters, C3-C20 ketones, polyethylene glycols, aliphatichydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons andcombinations thereof. Certain solvents that are volatile or non-volatilemay be utilized but may be desirably removed in the final parenteralpreparation to acceptable levels for parenteral administration. Inaddition mixtures of any two or more of the above solvents are alsoacceptable.

The composition of the present invention can comprise a pharmaceuticallyacceptable surfactant to provide a stable emulsion. The amount of thesurfactant present in the composition will vary depending on the amountof solvent for the propofol. For example, the surfactant is suitablypresent in an amount that is no more than 1% by weight of thecomposition for a formulation that contains 1 to 6% of water-immisciblesolvent, more preferably the amount of surfactant is 0.2 to 1.0% byweight of the composition, and even more preferably the amount ofsurfactant is 0.3-0.66% by weight of the composition. For a formulationthat contains 6 to 10% of water-immiscible solvent, a suitable amount ofsurfactant is no more than 5% by weight of the composition, andpreferably is 0.5 to 3% by weight of the composition, and morepreferably is 0.8-1.2% by weight of the composition. Acceptable range ofsurfactant concentration is 0.1-5%, more preferably, 0.2-3% and mostpreferably 0.3-0.8%. Suitable surfactants include synthetic non-ionicsurfactant such as ethoxylated ethers and esters such as Tween 80 andTocopherol polyethylene glycol stearate (Vitamin E-TPGS), andpolypropylene-polyethylene block co-polymers, and phosphatides orlecithins, for example naturally occurring phosphatides such as egg andsoya phosphatides, or egg and soya lecithins and modified orartificially manipulated phosphatides (for example those prepared byphysical fractionation and/or chromatography), or mixture thereof.Preferred surfactants are egg and soya phosphatides. Most preferred isegg lecithin.

It is well recognized that a surfactant can stabilize an emulsion byforming a stabilizing layer at the surface of the oil phase or dropletphase of the emulsion. The presence of protein such as albumin in thecomposition of the present invention has been found to stabilize theemulsion, with and without surfactant present in the composition. Forpropofol compositions of embodiments of the invention which containprotein, such as albumin as well as surfactant, it has been found thatthe emulsions are stabilized by the presence of albumin as well as thesurfactant in the stabilizing layer at the surface of the oil phase ordroplet phase of the emulsion. For propofol compositions of embodimentsof the invention which contain protein such as albumin, but nosurfactant, it has also been found that albumin is present on thedroplets of the oil phase of the emulsion and is included in thestabilizing layer. The total albumin measured in the droplet phase ofthe emulsion was at least 0.5-10% of the total albumin in theformulation. Thus the stabilizing layer in such invention formulationscomprises both the surfactant (e.g., lecithin) as well as the protein(albumin). The mean size of the droplets typically is in the range fromabout 20 nanometers to about 1000 nanometers, desirably from about 50nanometers to about 500 nanometers, and more desirably from about 100 toabout 300 nanometers.

Proteins contemplated for use as stabilizing agents or for purposes ofbinding free propofol to reduce pain in accordance with the presentinvention include albumins, globulins, immunoglobulins, lipoproteins,caseins, insulins, hemoglobins, lysozymes, alpha.-2-macroglobulin,fibronectins, vitronectins, fibrinogens, lipases, and the like.Proteins, peptides, enzymes, antibodies and combinations thereof, arecontemplated for use in the present invention. Preferred concentrationsof proteins are 0.01-5%, more preferably, 0.1-3% and most preferably0.2-1%. The preferred protein is albumin, most preferably human albuminor recombinant human albumin.

The composition of the present invention is suitably formulated to havea pH range of 4.5 to 9.0, preferably pH 5.0 to pH 7.5. A pH range of 6-8is also suitable. The pH can be adjusted as required by means of asuitable pH modifier, that is, a component that can be used to adjust pHto the desired range and yet is suitable for parenteral administration.The pH of the composition can be adjusted by the addition to theformulation of the pH modifier. It will also be understood that thewater of injection can include the pH modifier so the resultingcomposition has the desired pH range. Thus, by way of example, the pHmodifier can be added to the water of injection to achieve the desiredpH, and the pH-modified water of injection can then be used to make theformulation. The pH adjustment is a matter of processing choice.Suitable pH modifiers include alkali metal salts, such as sodiumhydroxide, and acids, including mineral acids such as hydrochloric acidand organic acids.

The composition of the present invention may be made isotonic with bloodby incorporation of a suitable tonicity modifier, for example glycerin.

The composition of the present invention comprises a pharmaceuticallyacceptable carrier. The carrier is preferably a pyrogen-free water orwater for injection U.S.P.

The present invention's composition is a sterile aqueous formulation andis prepared by standard manufacturing techniques using, for example,aseptic manufacture, sterile filtration or terminal sterilization byautoclaving.

The compositions of the present invention are useful as anesthetics,which include sedation, induction and maintenance of general anesthesia.Accordingly, in another aspect, the present invention provides a methodof producing anesthesia (including sedation, induction and maintenanceof general anesthesia) in a warm-blooded animal, including humans.

Producing anesthesia comprises administering parenterally a sterile,aqueous pharmaceutical composition which comprises an oil-in-wateremulsion in which neat propofol or propofol in a water-miscible or awater-immiscible solvent is emulsified with water and a surfactant.

Typically, dosage levels of propofol for producing general anesthesiaare from, about 2.0-2.5 mg/kg for an adult. Dosage for maintenance ofanesthesia is generally about 4-12 mg/kg/hr. Sedative effects may beachieved with, for example, a dosage of 0.3-4.5 mg/kg/hr. Dosage levelsof propofol for producing general anesthesia, induction and maintenance,and for producing a sedative effect, may be derived from the substantiveliterature and may be determined by one skilled in the art to suit agiven patient and treatment regime.

Accordingly, in one aspect, the present invention provides an optimizedformulation that comprises a sufficiently low amount of egg lecithinwhich is reduced from the industry standard of 1.2% by weight to about0.4% by weight. In another aspect, the present invention provides aformulation that comprises a low amount of soybean oil, which isdecreased from the industry standard of 10% by weight to 1-6% by weight,preferably 3% by weight. In yet another aspect, the present inventionprovides a formulation with a pH range of pH 5.0-8.5, preferably pH 6.0to 8.0. A pH 5.0 to 7.5, or pH 5.0 to 7.0 is also suitable. Variationsof pH, such as pH 7.0 to 8.5, are equally suitable.

In accordance with the present invention several advantages have beenfound, which include, no more than a ten-fold increase in the growth ofmicroorganism, such as S. aureus, E. coli, P. aeruginosa and C. albicansfor at least 24 hours, a reduction in the risk of hyperlipidemia,elimination of EDTA that may cause zinc loss and a reduction in the riskof pain due binding of free propofol with albumin.

The compositions of the present invention preferably are prepared by aprocess which is carried out under an inert atmosphere, since propofolis known to be sensitive to oxidation. Typically the process forpreparing the sterile emulsion for parenteral administration involvespreparation of the aqueous phase and preparation of the oil phase (inany order) and mixing the oil phase with the aqueous phase. In thepreferred method of making the propofol formulations of the invention,the aqueous phase is prepared by adding glycerin into water forinjection. Then other ingredients, if used, are added. For example, ifalbumin is included in the formulation, albumin is added to the aqueousphase, that is, to the water of injection. The oil phase can be neatpropofol or propofol added to a solvent for propofol. For example, thesolvent can be a water miscible solvent, such as methanol, or awater-immiscible solvent, such as soybean oil and/or other organicsolvent, as well as mixtures of solvents. The composition can alsoinclude a surfactant, and if surfactant is included in the composition,it can be added to either the aqueous phase or the oil phase dependingon the surfactant used. In a preferred method, surfactant, such aslecithin, is added to the oil phase and stirred until dissolved at about20° C.-60° C. The oil phase is added to the aqueous phase, and mixed toform the crude emulsion. In a preferred embodiment, the aqueous phaseincludes human serum albumin. The crude emulsion is homogenized at highpressure until the desired emulsion size is reached, and the pH isadjusted, if necessary. The emulsion is then sterile filtered to formthe final sterile emulsion, under inert atmosphere, preferably into aholding vessel. Sterile containers or vials can be filled from thesterile holding vessel, also under inert atmosphere.

In accordance with a further embodiment of the invention, the propofolformulation is stored in a container that includes a closure, and theclosure is inert or non-reactive with respect to propofol, such that theclosure does not cause degradation or loss in potency of propofolformulations. The closure can itself be inert or non-reactive, or theclosure can be coated with a suitable coating material to make itnon-reactive or inert. The container is also preferably inert ornon-reactive and/or the container is treated to be inert ornon-reactive. The invention is particularly advantageous for storingpropofol formulations that are susceptible to propofol degradation orpotency loss. For example, the invention is advantageous for storingpropofol formulations that contain less than about 10% (w/v),water-immiscible solvent for propofol, such as oil, preferably less than7% (w/v) water-immiscible solvent and more preferably less than 4% (w/v)water-immiscible solvent. Thus, it will be appreciated by those skilledin the art that the present invention can be used for any propofolformulation that contains insufficient propofol solvent to protect thepropofol from degradation or loss of potency. For example, the propofolcompositions described herein, as well as the sterile pharmaceuticalpropofol composition described in U.S. Pat. No. 5,637,625, thedisclosure of which is incorporated herein by reference, is, inaccordance with the present invention, stored in a container that has aninert or non-reactive closure. The '625 patent describes formulations ofpropofol as a phospholipid-coated microdroplet substantially completelydevoid of fats or triglycerides. The phospholipid-coated microdropletsat about 0.1 μm diameter droplet of drug in the oil state, coated with astabilizing monolayer of phospholipid are described in U.S. Pat. Nos.4,622,219 and 4,725,442, the disclosures of which are herebyincorporated by reference.

The coating material of the propofol microdroplet can be chosen from thelipids described in U.S. Pat. No. 4,725,442, cols. 5-7, particularly thephospholipids described in Class A, B and C. Additionally, themicrodroplet can be coated by certain mono-glycerides capable of formingoriented monolayers and bilayers in the presence of decane (Benz et al.Biochim. Biophys. Acta 394:323-334, 1975). Examples of usefulmono-glycerides include, but are not limited to, the following:

-   -   1-monopalmitoyl-(rac)-glycerol (Monopalmitin)    -   1-monocaprylol-(rac)-glycerol (Monocaprylin)    -   1-monooleoyl-(rac)-glycerol (C18:1, cis-9) (Monoolein)    -   1-monostearyl-(rac)-glycerol (Monostearin)        Phosphatidylcholine (lecithin) is the most useful example.

The preferred method of preparing propofol microdroplets described inthe '625 patent on the laboratory scale is sonication with a probesonicator. For industrial scale production, Microfluidization®(Microfluidics Corp., Newton, Mass. 02164) is preferred. The apparatusis described by Mayhew et al. in Biochim. Biophys. Acta 775:169-174,1984. Alternative industrial scalable processors include but are notlimited to the Gaulin and Ranni Homogenizers (APV Gaulin/RannieHomogenizers, St. Paul, Minn.).

Containers in which the propofol formulation can be stored include anycontainer that is suitable for storing a pharmaceutical. Typicalcontainers are made of glass and have been found to be inert topropofol. Treated glass containers such as siliconized glass containersare also useful. Plastic containers can also be used provided they areinert and/or are treated or coated to be inert. Suitable containersinclude vials, bottles, cartridges, syringes, pre-filled syringes andthe like. The container is preferably sealed with a closure, such as,for example, a rubber stopper, plunger, lid, top or the like.

Suitable inert or non-reactive stoppers may be obtained from severalcommercial manufacturers. In general the preferred closures are madewith inert, non-reactive materials with little to no leachables.Preferred closures also include those that are coated or treated withinert materials such as siliconized polymer or Teflon/fluoropolymercoated/treated closures. By way of example and not in limitation of thepresent invention, rubber closures that are suitable in the presentinvention include bromobutyl rubber, chlorobutyl rubber, fluoropolymers,silicones, siliconized bromobutyl rubber, and siliconized chlorobutylrubber, provided, as described, the closure is inert to propofol or itis treated or coated to be inert to propofol. For example, AmericanStelmi supplies elastomeric closures or stoppers such as the 6720/6722(models C1624, C1474) bromobutyl rubber or 6900 chlorobutyl rubber, someof which are suitable for propofol formulations because their use doesnot result in the degradation of propofol. Stoppers from other companiesare also useful, provided such stoppers do not cause the degradation ofpropofol. For example, West Pharmaceutical makes elastomeric closuressuch as its 4400 series including 4416/50 gray butyl, 4405/50 graybutyl, 4416/50 gray butyl with Silicone, 4432/50 gray butyl, 4432/50gray butyl with Silicone, 4432/50 gray butyl with Teflon, 4432/50 graybutyl with Silicone/Teflon, 4416/50 gray butyl with Teflon, 4405/50 graybutyl with Teflon, 4416/50 gray butyl, and also 1535 Red, PEP, and8312/43 clear. Alternate closures from other manufacturers such asHelvoet Pharma are also suitable for use for closures for propofolformulations provided they do not cause degradation or loss in potencyof propofol formulations.

Non-reactive, non-elastomeric closures are also useful. For example,non-rubber closures include metal closures, and plastics such aspolyethylene, polypropylene, nylon, polyurethane, polyvinylchloride,polyacrylates, polycarbonates, and the like that themselves do not causedegradation to propofol or that are treated or coated so as not to causedegradation of propofol.

The following examples illustrate, but do not limit, the inventiondescribed above.

Example 1

Propofol-albumin compositions containing no solvent and no addedsurfactant. An emulsion containing 3% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding humanserum albumin (3% by weight) into water for injection and stirred untildissolved. The aqueous phase was passed through a filter (0.2 umfilter). The oil phase consists of neat propofol (3% by weight). The oilphase was added to the aqueous phase and homogenized at 10,000 RPM for 5min. The crude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. The final emulsion was filtered (0.2μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; Glycerol 2.25%; water for injectionq.s. to 100; pH 5-8.

Example 2

Propofol-albumin compositions containing low solvent and no addedsurfactant. An emulsion containing 0.13% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding humanserum albumin (3% by weight) into water for injection and stirred untildissolved. The aqueous phase was passed through a filter (0.2 μmfilter). The oil phase consists of propofol (0.13% by weight) andmethanol (3%). The oil phase was added to the aqueous phase andhomogenized at 10,000 RPM for 5 min. The crude emulsion was highpressure homogenized at 20,000 psi and recirculated for up to 15 cyclesat 5° C. Alternately, discrete passes through the homogenizer were used.The emulsion is evaporated at reduced pressure to remove methanol. Thefinal emulsion was filtered (0.2 μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; Glycerol 2.25%; water for injectionq.s. to 100; pH 5-8.

Example 3

Propofol-albumin compositions containing no oil and with Tween 80surfactant. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding humanserum albumin (3% by weight) into water for injection and stirred untildissolved. The aqueous phase was passed through a filter (0.2 μmfilter). Surfactant, e.g., Tween 80 (0.5%), was added to aqueous phase.The oil phase consisted of neat propofol (1% by weight). The oil phasewas added to the aqueous phase and homogenized at 10,000 RPM for 5 min.The crude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. The final emulsion was filtered (0.2μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; Tween 80 0.1-2%; Glycerol 2.25%;water for injection q.s. to 100; pH 5-8.

Example 4

Propofol-albumin compositions containing no oil and with Vitamin E-TPGSsurfactant. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase was passedthrough a filter (0.2 μm filter). Surfactant, e.g., Vitamin E TPGS(0.5%), was added to aqueous phase. The oil phase consisted of neatpropofol (1% by weight). The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. The crude emulsion was highpressure homogenized at 20,000 psi and recirculated for up to 15 cyclesat 5° C. Alternately, discrete passes through the homogenizer were used.The final emulsion is filtered (0.2 μm filter) and stored undernitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; Vitamin E-TPGS 0.1-2%; Glycerol2.25%; water for injection q.s. to 100; pH 5-8.

Example 5

Propofol-albumin compositions containing no oil and with lecithinsurfactant. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding humanserum albumin (3% by weight) into water for injection and stirred untildissolved. The aqueous phase was passed through a filter (0.2 μmfilter). Surfactant, e.g., egg or soy lecithin (0.12%), was added topropofol. The oil phase consists of neat propofol (1% by weight). Theoil phase was added to the aqueous phase and homogenized at 10,000 RPMfor 5 min. The crude emulsion was high pressure homogenized at 20,000psi and recirculated for up to 15 cycles at 5° C. Alternately, discretepasses through the homogenizer were used. The final emulsion wasfiltered (0.2 μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-10%; human serum albumin 0.01-5%; egg or soy lecithin 0.1-5%;Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 6

Propofol-albumin compositions containing no oil and with lecithinsurfactant. An emulsion containing 1-10% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase was passedthrough a filter (0.2 μm filter). Surfactant, e.g., egg or soy lecithin(3.3%), was added to propofol. The oil phase consists of neat propofol(10% by weight). The oil phase was added to the aqueous phase andhomogenized at 10,000 RPM for 5 min. The crude emulsion was highpressure homogenized at 20,000 psi and recirculated for up to 15 cyclesat 5° C. Alternately, discrete passes through the homogenizer were used.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen. The formulation was also diluted with additional aqueous phaseto obtain suitable propofol concentrations, i.e., 1%, 2% and 5% inaddition to the 10% formulation. All of these formulations were found tobe stable. Adjustment of pH was made as necessary with standard pHmodifiers. Thus, a wide range of propofol concentrations at 10% andbelow were prepared by this method. Formulations with the followinggeneral ranges of components (weight %) for such propofol compositionswere prepared as follows: Propofol 0.5-10%; human serum albumin 0.01-5%;egg or soy lecithin 0.1-5%; Glycerol 2.25%; water for injection q.s. to100; pH 5-8.

Example 7

Propofol-albumin compositions containing no oil and with Pluronic F127surfactant. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase was passedthrough a filter (0.2 μm filter). Surfactant, e.g., pluronic F127(1.5%), was added to the aqueous phase. The oil phase consisted of neatpropofol (10% by weight). The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. The crude emulsion was highpressure homogenized at 20,000 psi and recirculated for up to 15 cyclesat 5° C. Alternately, discrete passes through the homogenizer were used.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen. The formulation was also diluted to obtain suitable propofolconcentrations e.g., 1%-5%.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-10%; human serum albumin 0.01-5%; pluronic F127 0.1-5%; Glycerol2.25%; water for injection q.s. to 100; pH 5-8.

Example 8

Propofol-albumin compositions containing oil and lecithin. An emulsioncontaining 1% (by weight) of propofol was prepared as follows. Theaqueous phase was prepared by adding glycerol (2.25% by weight) andhuman serum albumin (0.5% by weight) into water for injection andstirred until dissolved. The aqueous phase was passed through a filter(0.2 μm filter). The oil phase was prepared by dissolving egg lecithin(0.4% by weight) and propofol (1% by weight) into soybean oil (3% byweight) at about 50° C.-60° C. and stirred until dissolved. The oilphase was added to the aqueous phase and homogenized at 10,000 RPM for 5min. The crude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. The final emulsion was filtered (0.2μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-0.6%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 9

Propofol-albumin compositions containing oil (2%) and egg lecithin(0.3%). An emulsion containing 1% (by weight) of propofol was preparedas follows. The aqueous phase was prepared by adding glycerol (2.25% byweight) and human serum albumin (0.5% by weight) into water forinjection and stirred until dissolved. The aqueous phase was passedthrough a filter (0.2 μm filter). The oil phase was prepared bydissolving egg lecithin (0.3% by weight) and propofol (1% by weight)into soybean oil (2% by weight) at about 50° C.-60° C. and stirred untildissolved. The oil phase was added to the aqueous phase and homogenizedat 10,000 RPM for 5 min. The crude emulsion was high pressurehomogenized at 20,000 psi and recirculated for up to 15 cycles at 5° C.Alternately, discrete passes through the homogenizer were used. Thefinal emulsion was filtered (0.2 μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-0.6%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 10

Propofol-albumin compositions containing 1% oil. An emulsion containing1% (by weight) of propofol was prepared as follows. The aqueous phasewas prepared by adding glycerol (2.25% by weight) and human serumalbumin (3% by weight) into water for injection and stirred untildissolved. The aqueous phase was passed through a filter (0.2 μmfilter). The oil phase was prepared by dissolving propofol (1% byweight) into soybean oil (1% by weight) and stirred until dissolved. Theoil phase was added to the aqueous phase and homogenized at 10,000 RPMfor 5 min. The crude emulsion was high pressure homogenized at 20,000psi and recirculated for up to 15 cycles at 5° C. Alternately, discretepasses through the homogenizer were used. The final emulsion wasfiltered (0.2 μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; Glycerol2.25%; water for injection q.s. to 100; pH 5-8.

Example 11

Propofol-albumin compositions containing 5% oil and lecithin. Anemulsion containing 1% (by weight) of propofol was prepared as follows.The aqueous phase was prepared by adding glycerol (2.25% by weight) andhuman serum albumin (3% by weight) into water for injection and stirreduntil dissolved. The aqueous phase was passed through a filter (0.2 μmfilter). The oil phase was prepared by dissolving egg lecithin (0.5% byweight) and propofol (1% by weight) into soybean oil (5% by weight) andchloroform (3% by weight) and stirred until dissolved. The oil phase wasadded to the aqueous phase and homogenized at 10,000 RPM for 5 min. Thecrude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. The emulsion was evaporated underreduced pressure to remove the chloroform. The final emulsion wasfiltered (0.2 μm filter) and stored under nitrogen. Chloroform levels inthe final formulation were in the acceptable range for parenteraladministration of the propofol formulation.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-0.6%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 12

Propofol compositions containing 3% oil and lecithin (0.4%) with pH 7-8.An emulsion containing 1% (by weight) of propofol was prepared asfollows. The aqueous phase was prepared by adding glycerol (2.25% byweight) into water for injection and stirred until dissolved. Theaqueous phase pH was adjusted to pH 7-8 by addition of dilutehydrochloric acid or sodium hydroxide. The aqueous phase was passedthrough a filter (0.2 μm filter). The oil phase was prepared bydissolving egg lecithin (0.4% by weight) and propofol (1% by weight)into soybean oil (3% by weight) at about 50° C.-60° C. and stirred untildissolved. The oil phase was added to the aqueous phase and homogenizedat 10,000 RPM for 5 min. Further pH adjustment using either acid or basewas performed at this stage. The crude emulsion was high pressurehomogenized at 20,000 psi and recirculated for up to 15 cycles at 5° C.Alternately, discrete passes through the homogenizer were used. Final pHadjustment if necessary was performed at this stage. The final emulsionwas filtered (0.2 μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; soybean oil 0.5-6.0%; egg lecithin 0.1-1.2%; Glycerol 2.25%;water for injection q.s. to 100; pH 5-8. Other conventional surfactantssuch as vitamin E (TPGS), Tween 80 and Pluronic F127 were also used.

In general pH adjustment for different formulations of propofol was doneeither prior to emulsification or after the homogenization process.

Example 13

Propofol compositions containing 3% oil and lecithin (0.4%) with pH 6-7.An emulsion containing 1% (by weight) of propofol was prepared asfollows. The aqueous phase was prepared by adding glycerol (2.25% byweight) into water for injection and stirred until dissolved. Theaqueous phase pH was adjusted to pH 6-7 by addition of dilutehydrochloric acid or sodium hydroxide. The aqueous phase was passedthrough a filter (0.2 μm filter). The oil phase was prepared bydissolving egg lecithin (0.4% by weight) and propofol (1% by weight)into soybean oil (3% by weight) at about 50° C.-60° C. and stirred untildissolved. The oil phase was added to the aqueous phase and homogenizedat 10,000 RPM for 5 min. Further pH adjustment using either acid or basewas performed at this stage. The crude emulsion was high pressurehomogenized at 20,000 psi and recirculated for up to 15 cycles at 5° C.Alternately, discrete passes through the homogenizer were used. Final pHadjustment if necessary was performed at this stage. The final emulsionwas filtered (0.2 μm filter) and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; soybean oil 0.5-6.0%; egg lecithin 0.1-1.2%; Glycerol 2.25%;water for injection q.s. to 100; pH 5-8. Other conventional surfactantssuch as vitamin E (TPGS), Tween 80 and Pluronic F127 were also used.

Example 14

Propofol compositions containing no oil and with Tween 80 Surfactant. Anemulsion containing 1% (by weight) of propofol was prepared as follows.The aqueous phase was prepared by adding glycerol (2.25% by weight) intowater for injection and Tween 80 (0.5%) and stirred until dissolved. Theaqueous phase was passed through a filter (0.2 μm filter). The oil phaseconsists of neat propofol (1% by weight). The oil phase was added to theaqueous phase and homogenized at 10,000 RPM for 5 min. The crudeemulsion was high pressure homogenized at 20,000 psi and recirculatedfor up to 15 cycles at 5° C. Alternately, discrete passes through thehomogenizer were used. The final emulsion is filtered (0.2 μm filter)and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions prepared are as follows: Propofol 0.5-5%;Tween 80 0.1-2%; Glycerol 2.25%; water for injection q.s. to 100; pH5-8.

Example 15

Propofol-albumin compositions containing oil (3%) and lecithin (0.4%)with pH 7-8. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase pH wasadjusted to pH 7-8 by addition of dilute sodium hydroxide. The aqueousphase was passed through a filter (0.2 μm filter). The oil phase wasprepared by dissolving egg lecithin (0.4% by weight) and propofol (1% byweight) into soybean oil (3% by weight) at about 50° C.-60° C. andstirred until dissolved. The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. Further pH adjustment usingeither acid or base was performed at this stage. The crude emulsion washigh pressure homogenized at 20,000 psi and recirculated for up to 15cycles at 5° C. Alternately, discrete passes through the homogenizerwere used. Final pH adjustment if necessary was performed at this stage.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions prepared are as follows: Propofol 0.5-5%;human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 16

Propofol-albumin compositions containing oil (3%) and lecithin (0.4%)with pH 6-7. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase pH wasadjusted to pH 6-7 by addition of dilute hydrochloric acid. The aqueousphase was passed through a filter (0.2 μm filter). The oil phase wasprepared by dissolving egg lecithin (0.4% by weight) and propofol (1% byweight) into soybean oil (3% by weight) at about 50° C.-60° C. andstirred until dissolved. The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. Further pH adjustment usingeither acid or base was performed at this stage. The crude emulsion washigh pressure homogenized at 20,000 psi and recirculated for up to 15cycles at 5° C. Alternately, discrete passes through the homogenizerwere used. Final pH adjustment if necessary was performed at this stage.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions prepared are as follows: Propofol 0.5-5%;human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 17

Propofol-albumin compositions containing oil (3%) and lecithin (0.7%)with pH 6-7. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase pH wasadjusted to pH 6-7 by addition of dilute hydrochloric acid. The aqueousphase was passed through a filter (0.2 μm filter). The oil phase wasprepared by dissolving egg lecithin (0.7% by weight) and propofol (1% byweight) into soybean oil (3% by weight) at about 50° C.-60° C. andstirred until dissolved. The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. Further pH adjustment usingeither acid or base was performed at this stage. The crude emulsion washigh pressure homogenized at 20,000 psi and recirculated for up to 15cycles at 5° C. Alternately, discrete passes through the homogenizerwere used. Final pH adjustment if necessary was performed at this stage.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 18

Propofol-albumin compositions containing oil (3%) and lecithin (0.2%)with pH 6-7. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase pH wasadjusted to pH 6-7 by addition of dilute hydrochloric acid or otherappropriate agent. The aqueous phase was passed through a filter (0.2 μmfilter). The oil phase was prepared by dissolving egg lecithin (0.2% byweight) and propofol (1% by weight) into soybean oil (3% by weight) atabout 50° C.-60° C. and stirred until dissolved. The oil phase was addedto the aqueous phase and homogenized at 10,000 RPM for 5 min. Further pHadjustment using either acid or base was performed at this stage. Thecrude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. Final pH adjustment if necessary wasperformed at this stage. The final emulsion was filtered (0.2 μm filter)and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 19

Propofol-albumin compositions containing oil (3%) and lecithin (0.2%)with pH 7-8. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase pH wasadjusted to pH 7-8 by addition of dilute sodium hydroxide. The aqueousphase was passed through a filter (0.2 μm filter). The oil phase wasprepared by dissolving egg lecithin (0.7% by weight) and propofol (1% byweight) into soybean oil (3% by weight) at about 50° C.-60° C. andstirred until dissolved. The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. Further pH adjustment usingeither acid or base was performed at this stage. The crude emulsion washigh pressure homogenized at 20,000 psi and recirculated for up to 15cycles at 5° C. Alternately, discrete passes through the homogenizerwere used. Final pH adjustment if necessary was performed at this stage.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 20

Propofol-albumin compositions containing oil (6%) and lecithin (0.8%)with pH 7-8. An emulsion containing 2% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight) and human serum albumin (0.5% by weight) into waterfor injection and stirred until dissolved. The aqueous phase pH wasadjusted to pH 7-8 by addition of dilute sodium hydroxide. The aqueousphase was passed through a filter (0.2 μm filter). The oil phase wasprepared by dissolving egg lecithin (0.8% by weight) and propofol (2% byweight) into soybean oil (6% by weight) at about 50° C.-60° C. andstirred until dissolved. The oil phase was added to the aqueous phaseand homogenized at 10,000 RPM for 5 min. Further pH adjustment usingeither acid or base was performed at this stage. The crude emulsion washigh pressure homogenized at 20,000 psi and recirculated for up to 15cycles at 5° C. Alternately, discrete passes through the homogenizerwere used. Final pH adjustment if necessary was performed at this stage.The final emulsion was filtered (0.2 μm filter) and stored undernitrogen. This formulation was also further diluted with the aqueousphase to obtain a 1% propofol emulsion. Both the 1% and the 2%formulations were found to be satisfactory.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 21

Propofol-albumin compositions containing oil and lecithin added toaqueous phase. An emulsion containing 1% (by weight) of propofol wasprepared as follows. The aqueous phase was prepared by adding glycerol(2.25% by weight), and lecithin (0.4%) and heated 40-60° C. to obtain adispersion. Human serum albumin (0.5% by weight) was added into thecooled dispersion and stirred until dissolved. The oil phase wasprepared by dissolving propofol (1% by weight) into soybean oil (3% byweight) and stirred until dissolved. The oil phase was added to theaqueous phase and homogenized at 10,000 RPM for 5 min. The crudeemulsion was high pressure homogenized at 20,000 psi and recirculatedfor up to 15 cycles at 5° C. Alternately, discrete passes through thehomogenizer were used. The final emulsion was filtered (0.2 μm filter)and stored under nitrogen.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; human serum albumin 0.01-3%; soybean oil 0.5-6.0%; egg lecithin0.1-1.2%; Glycerol 2.25%; water for injection q.s. to 100; pH 5-8.

Example 22 Propofol Compositions Containing Oil (3%) and Lecithin (0.4%)with pH 7-8.5

An emulsion containing 1% (by weight) of propofol was prepared asfollows. The aqueous phase was prepared by adding glycerol (2.25% byweight) into water for injection and stirred until dissolved. Theaqueous phase pH was adjusted to pH 7-8.5 by addition of dilute sodiumhydroxide. The aqueous phase was passed through a filter (0.2 μmfilter). The oil phase was prepared by dissolving egg lecithin (0.4% byweight) and propofol (1% by weight) into soybean oil (3% by weight) atabout 50° C.-60° C. and stirred until dissolved. The oil phase was addedto the aqueous phase and homogenized at 10,000 RPM for 5 min. Further pHadjustment using either acid or base was performed at this stage. Thecrude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. Final pH adjustment if necessary wasperformed at this stage. The final emulsion was filtered (0.2 μm filter)and stored under nitrogen or argon.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; soybean oil 0.5-6.0%; egg lecithin 0.1-1.2%; Glycerol 2.25%;water for injection q.s. to 100; pH 5-8.5.

Example 23 Propofol Compositions Containing Oil (5%) and Lecithin (0.8%)with pH 7-8.5

An emulsion containing 1% (by weight) of propofol was prepared asfollows. The aqueous phase was prepared by adding glycerol (2.25% byweight) into water for injection and stirred until dissolved. Theaqueous phase pH was adjusted to pH 7-8.5 by addition of dilute sodiumhydroxide. The aqueous phase was passed through a filter (0.2 μmfilter). The oil phase was prepared by dissolving egg lecithin (0.8% byweight) and propofol (1% by weight) into soybean oil (5% by weight) atabout 50° C.-60° C. and stirred until dissolved. The oil phase was addedto the aqueous phase and homogenized at 10,000 RPM for 5 min. Further pHadjustment using either acid or base was performed at this stage. Thecrude emulsion was high pressure homogenized at 20,000 psi andrecirculated for up to 15 cycles at 5° C. Alternately, discrete passesthrough the homogenizer were used. Final pH adjustment if necessary wasperformed at this stage. The final emulsion was filtered (0.2 μm filter)and stored under nitrogen or argon.

Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-5%; soybean oil 0.5-6.0%; egg lecithin 0.1-1.2%; Glycerol 2.25%;water for injection q.s. to 100; pH 5-8.5.

Example 24 Oil-Free Propofol Compositions Containing Lecithin with pH7-8.5

An emulsion containing 1-10% (by weight) of propofol was prepared asfollows. The aqueous phase was prepared by adding glycerol (2.25% byweight) into water for injection and stirred until dissolved. Theaqueous phase pH was adjusted to pH 7-8.5 by addition of dilute sodiumhydroxide. A suitable buffer could be added into the aqueous phase ifnecessary. The aqueous phase was passed through a filter (0.2 μmfilter). Surfactant, e.g., egg or soy lecithin (3.3%), was added topropofol. The oil phase consisted of neat propofol (10% by weight). Theoil phase was added to the aqueous phase and homogenized at 10,000 RPMfor 5 min. Further pH adjustment was performed as necessary. The crudeemulsion was high pressure homogenized at 20,000 psi and recirculatedfor up to 15 cycles at 5° C. Alternately, discrete passes through thehomogenizer were used. The final emulsion was filtered (0.2 μm filter)and stored under nitrogen. The formulation was also diluted withadditional aqueous phase to obtain suitable propofol concentrations,i.e., 1%, 2% and 5% in addition to the 10% formulation. All of theseformulations were found to be stable. Adjustment of pH was made asnecessary with standard pH modifiers. Thus, a wide range of propofolconcentrations at 10% and below were prepared by this method.Formulations with the following general ranges of components (weight %)for such propofol compositions were prepared as follows: Propofol0.5-10%; egg or soy lecithin 0.1-5%; Glycerol 2.25%; water for injectionq.s. to 100; pH 5-8.5.

Example 25 Test for Bacterial Inhibition of Propofol Formulations

The objective of these tests was to determine the growth inhibition ofmicroorganisms in different propofol formulations prepared as above.Approximately 100-200 colony forming units (CFU) per ml of four standardU.S.P. organisms E. coli (ATCC 8739), S. aureus (ATCC 6538), C. albicans(ATCC 10231) and P. aeruginosa (ATCC 9027) for preservative tests wereinoculated in each formulation batch samples and incubated at 25° C.±1°C. The viable count of the test organism was determined at 0 hours, 24hours and 48 hours after inoculations. Not more than 10-fold increase ingrowth of microorganisms at 24 hours after microbial contaminationindicates the formulation is effective in inhibition of growth.

About 100-600 μL (approx. 100-200 CFU/ml) of each strain were inoculatedinto 2 ml of each tested batch sample tube (duplicated for each sample)and 2 ml TSB as control. Tryptic Soy Agar (TSA) plates were inoculatedwith 10% of the samples (20 drops of a 10 μL sterile disposable loop),duplicated for each sample. The TSA plates were inoculated aerobicallyat 25° C.±1° C. in the temperature controlled incubator. The colonycount of the test organism and the CFU/ml were determined at 0 hour, 24hours and 48 hours post microbial inoculation. The ratio of 24 hourscounts vs. 0 hour counts and ratio of 48 hours counts vs. 0 hour countswere determined to evaluate the effectiveness in inhibition of microbialgrowth. Results with a ratio less than 10 indicated that the testedsample had the inhibition effect on the microbial growth.

The antimicrobial effects of the propofol invention compositions aresummarized in the following tables.

TABLE 1 Microbial Growth against E. coli Ratios of CFU FormulationDescription relative to 0 hr pH % Oil % Lecithin 24 hr 48 hr 6.2 3 0.7 00 6.1 3 0.2 N/D N/D 7.93 3 0.2 N/D N/D 7.5 3 0.4 0 0 6 3 0.4 0 0 7.6 30.4   0.64 0 7.2 6 0.8 N/D N/D

TABLE 2 Microbial Growth against S. aureus Ratios of CFU FormulationDescription relative to 0 hr pH % Oil % Lecithin 24 hr 48 hr 6.2 3 0.7N/D N/D 6.1 3 0.2 N/D N/D 7.93 3 0.2 N/D N/D 7.5 3 0.4 0.52  1.41 6 30.4 N/D N/D 7.6 3 0.4 0.67 0.4 7.2 6 0.8 0   0  

TABLE 3 Microbial Growth against C. albicans Ratios of CFU FormulationDescription relative to 0 hr pH % Oil % Lecithin 24 hr 48 hr 6.2 3 0.7N/D N/D 6.1 3 0.2 0.04 1 7.93 3 0.2 0.01 0.03 7.5 3 0.4 0.28 0.34 6 30.4 1.29 0.57 7.6 3 0.4 0.47 0.44 7.2 6 0.8 0 0

TABLE 4 Microbial Growth against P. aeruginosa Ratios of CFU FormulationDescription relative to 0 hr pH % Oil % Lecithin 24 hr 48 hr 6.2 3 0.7N/D N/D 6.1 3 0.2 N/D N/D 7.93 3 0.2 N/D N/D 7.5 3 0.4 N/D 0.58 6 3 0.4N/D 3.67 7.6 3 0.4 0 0   7.2 6 0.8 N/D N/D

The variation of pH between about pH 6 to pH 8 did not have anysignificant impact on the bacterial growth profile. In addition, alecithin range of 0.2-0.7 did not impact bacterial growth. An oilconcentration in the range of 3-6% did not significantly impactbacterial growth. In the case of all the formulations above it was notedthat the strains of bacteria tested did not show an increase greaterthan 10 fold in 24 or 48 hours under the experimental conditions tested.

Example 26 Presence of Protein as Part of the Stabilizing Layer inPropofol Formulations

Propofol-albumin compositions described above containing no oil or lowamount of solvent (oil) are stabilized by the presence of albumin aswell as the surfactant if such surfactant is present. It is wellrecognized that a surfactant can stabilize an emulsion by forming astabilizing layer at the surface of the oil phase or droplet phase ofthe emulsion. In the case of invention compositions containing albumin,it is found that albumin is also present on the droplets of the oilphase of the emulsion. Two propofol formulations (a) containing no oil,but with propofol (1%), lecithin (0.33%) and albumin (0.5%) and (b)containing 3% soybean oil and propofol (1%), lecithin (0.4%) and albumin(0.5%) were centrifuged at 14000×g to separate the aqueous and oilphases. The oil phase was removed, washed, recentrifuged and separatedtwice. The separated oil phases were then resuspended in water forinjection and the protein content analyzed by using size exclusionchromatography on an HPLC. Albumin was detected in these samples at awavelength of 228 nm and 280 nm. The total albumin measured in thedroplet phase of the emulsion was at least 1-8% of the albumin in theformulation. This indicated that albumin was adsorbed on the droplets ofneat propofol or soybean oil/propofol as part of the stabilizing layer.Thus the stabilizing layer in such invention formulations comprises boththe surfactant (e.g., lecithin) as well as the protein (albumin).

Example 27 Binding of Propofol to Albumin

Addition of albumin to propofol formulations was surprisingly found tobind the free propofol in these formulations. The binding of propofol toalbumin was determined as follows. Solubility of propofol was tested inwater and in solutions containing albumin. 250 μL of propofol was addedto 10 ml of the water or albumin solution and stirred for 2 hours in ascintillation vial. The solution was then transferred to a 15 mlpolyethylene centrifuge tube and kept at 40° C. for about 16 hours.Samples of water and albumin solutions were assayed for propofol.Solubility of propofol in water was determined to be 0.12 mg/ml.Solubility of propofol in albumin solutions was dependent on theconcentration of albumin and increased to 0.44 mg/ml when the albuminconcentration was 2% (20 mg/ml). The solutions were ultrafilteredthrough a 30 kD MWCO filter and the filtrates assayed for propofol byHPLC. It was found that for the propofol/water solution, 61% of thepropofol could be recovered in the filtrate whereas for thepropofol/albumin solution, only 14% was recovered in the filtrateindicating a substantial binding of propofol with albumin. Based on thisresult, addition of albumin to formulations of propofol result in adecrease in the amount of free propofol due to albumin binding of thepropofol. This can result in a decrease in side effects ofadministration such as venous irritation, pain, etc.

Example 28 Reduction of Free Propofol in Formulations Containing Albumin

To further test the binding of free propofol to albumin in an emulsionformulation of propofol, albumin was added to Diprivan® at differentconcentrations (0.5%, 2% and 5%). The amount of free propofol wasmeasured as described above by ultrafiltration of the samples followedby HPLC assay for free propofol. The concentrations of free propofol inthe albumin containing formulations were compared a control sample (0%albumin) of albumin-free Diprivan®. Each of the tests was done intriplicate. The concentrations of free propofol in the 0.5%, 2% and 5%albumin-containing Diprivan® samples respectively were reduced by 22%,56% and 78% respectively. Similar results were obtained for inventionformulations of propofol. Once again, based on these results, thepresence of albumin in invention formulations of propofol results in adecrease in the amount of free propofol due to albumin binding of thepropofol. This in turn results in a decrease in side effects ofadministration such as venous irritation, pain, etc.

Example 29 Clinical Trials to Determine Pain

A randomized, double-blind clinical trial was conducted to compareadverse skin sensations of the propofol formulations of embodiments ofthe invention which contain albumin with that of a commerciallyavailable propofol formulation, Diprivan®. Trials were conducted incompliance with Good Clinical Practices and “informed consent” was takenfrom the subjects. Adult human subjects of either sex were eligible forparticipation if they had unbroken, apparently normal skin on the dorsalside of their hands.

The formulations originally stored in a refrigerator were brought toroom temperature and then 10 μL of the formulations was placed slowly onthe back side of both the hands of a subject simultaneously. The overallreaction and feel on their hands for the formulations were noted.

% of subjects with Albumin- % of subject with Propofol sensationDiprivan ® sensation Mild warm or Mild warm or Order of a test stingingNo stinging No on a subject or biting sensation or biting sensation1^(st) incidence 0.0 100.0 75 25

Example 30 Anesthetic Effect of Propofol Formulations Containing Low andNo Oil in Rats

The anesthetic effect and potency of the propofol formulations inaccordance with embodiments of the present invention and containing 0%and 3% soybean oil were compared with those of propofol in 10% soybeanoil emulsion (Diprivan®) in rats. Male Sprague-Dawley rats were assignedto six groups (n=10 in each) to receive single i.v. bolus doses of theformulations. Righting reflex and response to tail clamping wereassessed at periodic intervals. The loss of righting reflex and loss ofresponse to tail clamp were used as measures of hypnosis andantinocifensive response, respectively. Nocifensive stimuli were testedby application of a 2-cm serrated alligator clip to the middle third ofthe tail. Data were analyzed with repeated measures ANOVA.

There were no significant differences in the number of rats whoexhibited loss of righting reflex or loss of response to tail clampafter i.v. injection of a 10 mg/kg dose of the three preparations ofpropofol. However, at 5 mg/kg dose, significantly greater number of ratswho received oil-free preparation exhibited loss of righting reflex andloss of response to tail clamp at 2 min compared to those who receivedDiprivan®. Intravenous injection of the vehicle did not affect rightingreflex or tail clamp response.

This study demonstrated that decreasing the concentrations of soybeanoil did not affect the anesthetic properties of propofol in rats. Thetransient increase of activity seen with 5 mg/kg dose of the oil-freepreparation may be attributed to the increased availability of free drugdue to absence of oil. Decreasing or eliminating soybean oil frompropofol is beneficial in preventing hyperlipidemia seen with currentformulations of propofol.

Example 31 Method for Testing Compatibility of Propofol Emulsions

The following method was used for accelerated testing of propofolemulsions and the effect of different closures on propofol degradationor potency. Propofol emulsions (1-5 ml) were added into glass vials(5-20 ml) or other suitable vials, sealed with appropriate closures tobe tested and mounted on a multi-arm reciprocating shaker device[Burrell Scientific, Model 75]. The device is capable of agitating thevials in a reciprocating manner with control over the amplitude ofshaking stroke. The vials were agitated at a frequency of about 300-400cycles/minute. The samples were mounted on the shaker at roomtemperature for 16 hours. An HPLC assay of the propofol samples beforeand after the treatment determined if there was a loss in the potency orconcentration of propofol in the formulations. This method allowed therapid testing of closure compatibility with different propofolformulations as well as the emulsion stability. Closures tested in thisstudy were standard serum vial closures such as those prepared frombromobutyl rubber, chlorobutyl rubber, rubber closures with coatedTeflon, or fluorotec closures, siliconized closures, closures forscintillation vials (non-rubber, aluminium/metal backing). Suchclosures/vials were obtained from sources such as Wheaton, Stelmi, West,Dalkyo, Helvoet.

In the examples below, the following stoppers were used.

Closure code Closure type Composition type Rubber 1 Rubber Bromobutylrubber Rubber 2 Stelmi 6720(C1624) Bromobutyl rubber Rubber 3 Stelmi6720(C1474) Bromobutyl rubber Rubber 4 Stelmi 6900 Chlorobutyl rubberTeflon face 1 West 4405/50 Teflon Butyl rubber with fluoropolymer Teflonface 2 West 4432/50 Teflon Butyl rubber with fluoropolymer Teflon face 3GC teflon seal fluoropolymer Metal face Scintillation vial cap Metal

Example 32 Rubber Closure vs. Coated/Inert Closure for Oil-Free PropofolFormulations

Propofol formulations devoid of any oils were prepared as describedabove. These formulations contained approximately 1% (w/v) propofol.Several vials of samples with different closures were prepared. Theformulations were loaded on the shaking device as described above for 16hours. The HPLC assays for propofol content post-shaking were comparedto the original (control) samples to obtain the % recovery of propofol.The results are shown in the table below.

Composition of Formulations Propofol % % % % Closure conc Soybean Oillecithin albumin propofol Type % of Control 0 0.33 0.5 1 Rubber 1 23.2 00.33 0.5 1 Rubber 2 35.9 0 0.33 0.5 1 Rubber 3 45.0 0 0.33 0.5 1 Rubber4 44.1 0 0.33 0.5 1 Teflon face 1 101.0 0 0.33 0.5 1 Teflon face 3 97.90 0.33 0.5 1 Metal face 100.0 0 0.33 0 1 Rubber 1 27.3 0 0.33 0 1 Teflonface 2 99.9

A substantial drop of propofol concentration was seen for closuresRubber 1-4 indicating incompatibility of the closure material andpropofol, leading to the degradation of propofol and loss of potency ofthe formulation. Only 23-45% of the original propofol concentration wasrecovered for these rubber closures. In case of the Teflon facedstoppers and the metal-faced stopper, close to 100% of the originalpotency of propofol was retained. This effect was independent of whetherthe formulation contained albumin or not. This surprising findingindicates that propofol formulations containing no oil must be stored incontainers with either closures that are coated with inert materials ormade entirely of inert materials to avoid a potency drop or degradationof propofol.

Example 33 Rubber Closure vs. Coated/Inert Closure for 3% Oil PropofolFormulations

Propofol formulations containing 3% soybean oil were prepared asdescribed above. These formulations contained approximately 1% (w/v)propofol. Several vials of samples with different closures wereprepared. The formulations were loaded on the shaking device asdescribed above for 16 hours. The HPLC assays for propofol contentpost-shaking were compared to the original (control) samples to obtainthe recovery of propofol. The results are shown in the table below.

Composition of Formulations Propofol % % % % Closure conc Soybean Oillecithin albumin propofol Type % of Control 3 0.4 0.5 1 Rubber 1 52.9 30.4 0.5 1 Rubber 2 93.4 3 0.4 0.5 1 Rubber 3 99.9 3 0.4 0.5 1 Rubber 495.8 3 0.4 0.5 1 Teflon face 1 101.1 3 0.4 0.5 1 Teflon face 2 103.3

One of the three rubber closures used (Rubber 1) showed a loss inpotency of about 47% of the propofol. The Rubber 2, 3 and 4 as well asthe Teflon face 1 and 2 showed either no loss in propofol potency ormarginal (<7%) loss in propofol potency. Compared to the oil freeformulations, a surprisingly lesser amount of potency loss was observedwith the same rubber closures when the formulations contained 3% oil.This surprising finding indicates that soybean oil in propofolformulations protects the propofol from potential degradation. However,certain rubber compositions may still cause degradation of the propofol,and even with propofol compositions which include soybean oil,containers with inert closures are preferred.

Example 34 Effect of Oil Concentration on Propofol Potency with RubberClosures

Propofol formulations containing 0, 2, 3, 5% soybean oil were preparedas described above. A 10% soybean oil formulation (Diprivan®) was alsoobtained for this study. These formulations all contained approximately1% (w/v) propofol. Several vials of samples with rubber (Rubber 1)closures were prepared. The formulations were loaded on the shakingdevice as described above for 16 hours. The HPLC assays for propofolcontent post-shaking were compared to the original (control) samples toobtain the recovery of propofol. The results are shown in the tablebelow.

Composition of Formulations % % % % Closure Propofol conc Soybean Oillecithin albumin propofol Type % of Control 10* 1.2 0 1 Rubber 1 99.3 50.8 0.2 1 Rubber 1 82.9 3 0.4 0.5 1 Rubber 1 52.9 0 0.33 0.5 1 Rubber 123.2 0 0.33 0 1 Rubber 1 27.3 *Commercially available Diprivan ®.

The data shows that the oil in the formulation protected propofol fromdegradation. As the percent of oil in the formulation was decreased, thepotency of propofol also decreased confirming that the oil had aprotective effect on propofol. However at oil concentrations of 3% and5%, an approximately 47% and 17% loss in propofol potency was notedindicating that an inert closure material was essential for formulationsof propofol containing less than 10% oil.

Example 35 Rubber Closure v. Coated/Inert Closure for Albumin andNon-Albumin Propofol Formulations

Propofol formulations devoid of oils were prepared as described above.These formulations contained approximately 1% (w/v) propofol. Theseformulations were prepared either with human albumin or without humanalbumin to elucidate if albumin had any effect on propofol degradation.Several vials of samples with different closures were prepared. Theformulations were loaded on the shaking device as described above for 16hours. The HPLC assays for propofol content post-shaking were comparedto the original (control) samples to obtain the % recovery of propofol.The results are shown in the table below.

Composition of Formulations Propofol % % % % Closure conc Soybean Oillecithin albumin propofol Type % of Control 0 0.33 0.5 1 Rubber 1 23.2 00.33 0.5 1 Teflon face 1 101.0 0 0.33 0 1 Rubber 1 27.3 0 0.33 0 1Teflon face 2 99.9

With each of the rubber closures tested, a substantial drop of propofolconcentration was seen indicating incompatibility of the closurematerial. Only 23-27% of the original propofol concentration wasrecovered for the rubber closures. This effect was independent ofwhether the formulation contained albumin or not. In case of the Teflonfaced stoppers, approximately 100% of the original potency of propofolwas retained. This effect was independent of whether the formulationcontained albumin or not. Thus, the presence of albumin in inventionformulations did not affect the degradation of propofol.

Example 36 Effect of Additives Such as EDTA and Sodium Metabisulfite

Sodium metabisulfite and EDTA are both used in commercially availablepreparations of propofol containing 10% oil. To test if any of theseadditives provided a protective effect on propofol degradation in theaccelerated testing described above, these additives were also tested informulations of propofol containing no oil. Disodium EDTA was used at aconcentration of 0.0055% (as in Diprivan® and sodium metabisulfite wasadded at a concentration of 0.1% (as in the Gensia-Sicor product). Theresults are tabulated below:

Composition of Formulations Closure Propofol conc Additive % Soybean Oil% lecithin % albumin % propofol Type % of Control 0 0.33 0.5 1 Teflonface 1 101.0 0 0.33 0 1 Rubber 1 27.3 0 0.33 0.5 1 Rubber 1 25.0 0.0055%EDTA 0 0.33 0.5 1 Rubber 1 15.9 0.1% metabisulfite 0 0.33 0.5 1 Rubber 117.4

The results above indicated that commercial additives EDTA and sodiummetabisulfite do not play a role in preventing propofol degradation ifthe closure is not inert to propofol. Therefore the presence of 10% oilin the commercial formulations appears to be the major protective factorfor preventing propofol degradation in the absence of non-reactive orinert closures, as described herein.

Example 37 Shelf Stability of Propofol Formulations

Propofol formulations prepared as above were tested for shelf stabilityin serum vials stoppered with rubber closures of the type “Rubber 1.”The different formulations were placed in stability chambers with acontrolled environment of 40° C. and 75% relative humidity for up to twomonths. Propofol concentrations in the formulations were compared totheir respective time zero values. Results are tabulated below:

Composition of Formulations % % % % Closure Propofol Soybean Oillecithin albumin propofol Type conc % 0 0.33 0.5 1 Rubber 1 34.3* 3 0.40.5 1 Rubber 1 72.1 5 0.8 0.5 1 Rubber 1 89.6 10 1.2 0 1 Rubber 1 96.8*data at 2 weeks, rest of data at 2 months

These results confirmed the degradation of propofol as a result ofincompatibility with the rubber closures when vials containing differentpropofol samples were placed in a stability chamber at standardaccelerated shelf-stability conditions. Surprisingly, the samples withhigher amount of oil showed a greater degree of protection fromdegradation. There was minimal (within limits of experimental error) tono degradation in the sample containing 10% oil, but increasinglygreater amounts of degradation, approximately 10% and 28% respectivelyfor samples containing 5% and 3% oil and substantially higherdegradation for the sample without oil. Since a similar result wasobtained in the shaker test described above, it was concluded that theshaker test, for which results could be obtained within 24 hours, was asuitable surrogate for accelerated testing in conventionalshelf-stability chambers, and confirmed the surprising and unexpectedfinding that inert or non-reactive container closures are essential toprevent propofol degradation or loss of propofol potency in propofolformulations with less than 10% oil.

What is claimed is:
 1. A container storing an anesthetic, comprising: acontainer sealed by a closure and storing a liquid anesthetic solution,the anesthetic being from 0.1% to 10% by weight of the liquid anestheticsolution, the container being made of a material that is inert to theanesthetic, and the closure being made of siliconized rubber or a metal,wherein a concentration of the anesthetic in the liquid anestheticsolution stored in the container following a predetermined time periodis at least 93% of a concentration of the anesthetic in the liquidanesthetic solution before the liquid anesthetic solution is stored inthe container.
 2. The container of claim 1, wherein the anesthetic ispropofol.
 3. The container of claim 1, wherein the container is selectedfrom the group consisting of a vial, a bottle, a cartridge, a syringe,and a pre-filled syringe.
 4. The container of claim 1, wherein thematerial that is inert to the anesthetic is glass.
 5. The container ofclaim 4, wherein the glass is siliconized glass.
 6. The container ofclaim 1, wherein the material that is inert to the anesthetic isplastic.
 7. The container of claim 1, wherein the closure is selectedfrom the group consisting of a stopper, a plunger, a lid, and a top. 8.The container of claim 1, wherein the siliconized rubber is siliconizedbromobutyl rubber.
 9. The container of claim 1, wherein the siliconizedrubber is siliconized chlorobutyl rubber.
 10. The container of claim 1,wherein the metal is aluminum.
 11. The container of claim 1, wherein thepredetermined time period is 16 hours, and the concentration of theanesthetic in the liquid anesthetic solution stored in the containerfollowing 16 hours is at least 93% of a concentration of the anestheticin the liquid anesthetic solution before the liquid anesthetic solutionis stored in the container.
 12. The container of claim 1, wherein theliquid anesthetic solution further comprises water and a solvent. 13.The container of claim 12, wherein the solvent is from 0% to 10% byweight of the liquid anesthetic solution.
 14. The container of claim 12,wherein the solvent is a water-immiscible solvent.
 15. The container ofclaim 14, wherein the water-immiscible solvent is selected from thegroup consisting of soybean oil, safflower oil, cottonseed oil, cornoil, coconut oil, sunflower oil, arachis oil, castor sesame oil, orangeoil, limonene oil, olive oil, hydrogenated castor oil, marine oil,fractionated oil, an ester of a medium-chain fatty acid, an ester of along-chain fatty acid, a chemically modified palmitate, a glyceralester, a polyoxyl, and mixtures thereof.
 16. The container of claim 1,wherein the liquid anesthetic solution further comprises a surfactant.17. The container of claim 16, wherein the surfactant is selected fromthe group consisting of phosphatides, synthetic phospholipids, naturalphospholipids, lecithins, ethoxylated ethers, ethoxylated esters,tocopherol polyethylene glycol stearate, polypropylene-polyethyleneblock co-polymers, polyvinyl pyrrolidone, polyvinylalcohol, andcombinations thereof.
 18. The container of claim 17, wherein thesurfactant is selected from the group consisting of egg phosphatides,soya phosphatides, egg lecithins, soya lecithins, and combinationsthereof.
 19. A container storing propofol, comprising: a containersealed by a closure and storing a liquid propofol solution, the liquidpropofol solution comprising: propofol from 0.1% to 10% by weight of theliquid propofol solution, water, a solvent, a surfactant, and a tonicityagent, wherein: the container is made of a material that is inert to thepropofol, the closure is made of siliconized rubber or a metal, and aconcentration of the propofol in the liquid propofol solution stored inthe container following a predetermined time period is at least 93% of aconcentration of the propofol in the liquid propofol solution before theliquid propofol solution is stored in the container.
 20. A containerstoring propofol, comprising: a container sealed by a closure andstoring a liquid propofol solution, the liquid propofol solutioncomprising: propofol from 0.1% to 10% by weight of the liquid propofolsolution, water, soybean oil, egg phosphatide, and glycerin, wherein:the container is made of a material that is inert to the propofol, theclosure is made of siliconized rubber or a metal, and a concentration ofthe propofol in the liquid propofol solution stored in the containerfollowing a predetermined time period is at least 93% of a concentrationof the propofol in the liquid propofol solution before the liquidpropofol solution is stored in the container.